ERBB2 and lung cancer: Breast cancer is the most common malignant tumor in women, accounting for 30% of all malignant tumors.[23] In addition, it is prone to brain metastasis, second only to lung cancer, accounting for 15 to 20% of all brain metastases.[24,25] In recent years, the incidence of breast cancer brain metastases (BCBM) has increased and HER2 + and Triple-negative subtypes were had a higher rate of brain metastases.[26] Although significant progress has been made in the systematic treatment of BC that of BCBM is still very difficult.